(A) Field of the Invention
This invention relates to the polishing of plastic surfaces by means of a solvent vapor which permits penetration of solvent into the surface of a plastic article and creates an improved smoother surface after drying.
(B) History of the Prior Art
In the prior art, coating and plastic industries have always had some difficulty obtaining smooth, even and high gloss coatings or surfaces without exercising extreme care in the application or manufacture of a plastic or plastic coated article. The obtaining of smooth surfaces was usually accomplished by polishing, buffing or thermal baking techniques. Recently, it has been found that smooth surfaces can be obtained by spraying a solvent against a plastic surface to remove oxidized plastic and to dissolve uncovered plastic which, upon removal of the solvent, will form a smooth or fresh surface of clean plastic. Optionally, the surface could be treated with a solvent vapor which permits penetration of the liquid solvent deeper into the article, see eg. U.S. Pat. Nos. 3,327,033; 3,632,404 and 3,437,727.
Prior art vapor finishing processes and apparatus were usually cumbersome and complicated since the polishing operation required moving and handling the article through the apparatus, see eg. U.S. Pat. Nos. 3,737,499 and 3,020,661. Such processes and apparatus have definite disadvantages since the handling of the plastic article could itself result in marring the surface. Furthermore, the large complicated apparatus is generally too costly for general use.